Oilsands mixed with water has leaked in northeastern Alberta.

The Alberta Energy Regulator says Canadian Natural Resources Limited reported Monday that bitumen emulsion has been released on the Cold Lake Air Weapons Range.

The regulator put out a news release about it on Thursday.

Regulator spokesman Bob Curran says it's not clear how much has leaked or what caused the release from CNRL's high-pressure cyclic steam project.

Curran says the oilsands mixture has affected a nearby slough.

There were no injuries.

Curran also says it's also unclear if CNRL has stopped the flow of the bitumen emulsion, adding it's believed to be a slow seeping of the product underground that's come to the surface.

He says AER staff were onsite and working with the company.

"The company is responsible for the facility, they're responsible for operating it appropriately and they're responsible for fixing anything that goes wrong with it and our role is to come in and oversee those actions to ensure they're appropriate," Curran said.

He also says it's unknown when the spill actually occurred.

"They are required to notify us as soon as they realize they have a problem, so the moment they discovered it they would be required to report it to us."